Perfume

===Reverse engineering===
Creating perfumes through reverse engineering with analytical techniques such as [[Gas chromatography–mass spectrometry]] (GC/MS) can reveal the "general" formula for any particular perfume. The difficulty of GC/MS analysis arises due to the complexity of a perfume's ingredients. This is particularly due to the presence of natural essential oils and other ingredients consisting of complex chemical mixtures. However, "anyone armed with good GC/MS equipment and experienced in using this equipment can today, within days, find out a great deal about the formulation of any perfume... customers and competitors can analyze most perfumes more or less precisely."<ref>Calkin, Robert R. & Jellinek, J. Stephen (1994). "Perfumery: practice and principles". ''John Wiley & Sons, Inc.''. {{ISBN|0-471-58934-9}}</ref>

Antique or badly preserved perfumes undergoing this analysis can also be difficult due to the numerous degradation by-products and impurities that may have resulted from breakdown of the odorous compounds. Ingredients and compounds can usually be ruled out or identified using [[gas chromatograph]] (GC) smellers, which allow individual chemical components to be identified both through their physical properties and their scent. Reverse engineering of best-selling perfumes in the market is a very common practice in the fragrance industry due to the relative simplicity of operating GC equipment, the pressure to produce marketable fragrances, and the highly lucrative nature of the perfume market.<ref name=cbyear/>